In general, the use of olefinic impact modifiers in polyester compositions to provide molded articles having improved mechanical properties, particularly improved impact resistance has been well known. U.S. Pat. No. 4,172,859 claims polyester blends including ethylene/methyl acrylate/glycidyl acrylate polymers. U.S. Pat. No. 4,753,980 refers to polyester compositions comprising 60-97 weight percent of a polyester matrix (e.g., PBT and/or PET) and 3 to 40 weight percent of an ethylene copolymer of the formula E/X/Y, where E is a radical formed from ethylene; Y is selected from the group consisting of glycidyl methacrylate and glycidyl acrylate and X is a radical formed from ##STR1## where R.sup.1 is alkyl of 2 to 8 C, and R.sup.2 is H, CH.sub.3 or C.sub.2 H.sub.5. These compositions contain an ethylene/acrylic polymer where R.sup.1 of radical X is methyl. This patent refers to ethylene/butylacrylate/glycidyl methacrylate modifiers as superior to ethylene/methacrylate/glycidyl methacrylate modifiers at lower temperatures.
U.S. Pat. No. 5,175,204 refers to thermoplastic resin compositions which comprise an aromatic polyester and 1 to 50% by weight of a multi-phase structure thermoplastic polyester which is a graft copolymer of 5 to 95% by weight of epoxy group-containing ethylene copolymer and 95-5% by weight of a vinyl polymer or copolymer obtained from at least one vinyl monomer.
These, and other compositions of the prior art are used as materials for industrial parts, electrical and electronic machine parts, automobiles parts and the like. See, also, U.S. Pat. Nos. 4,140,670; 3,368,995; Re. 32,334; 4,499,239; 4,694,042; 5,407,706 and 5,543,464, among others.
There remains a need in the art for polyester based resins which have the improved qualities of toughness, i.e., resistance to impact, as well as melt flow properties enabling the use thereof in molded forms.